It is known that brake pressure communicated to a wheel assembly can be relieved during a braking application to control a skidding condition for the wheel assembly. In addition, with a pair of driving wheels it is possible to communicate pressurized fluid to one of the pair of wheel assemblies which is spinning in order to transfer driving torque to the other driving wheel via a differential between the pair of driving wheels. In order to compensate for skidding and spinning, an electronic control unit generally cooperates with a modulator valve to control communication of pressurized fluid to the wheel assembly. As the modulator valve operates during braking, skidding and spinning to control communication of pressurized fluid to the wheel assembly, it is desirable to provide a modulator valve which is simple in structure, yet compactly arranged to control communication from a fluid pressure generator to a wheel assembly.